FULL PRODUCT VERSION :
java version "1.6.0"
Java(TM) SE Runtime Environment (build 1.6.0-b105)
Java HotSpot(TM) Server VM (build 1.6.0-b105, mixed mode)


A DESCRIPTION OF THE PROBLEM :
When parsing huge XML files (> 200MB) with SAX Java 6 runs out of memory, because the whole input file is stored in memory. Java 1.5 and the current Xerces version 2.9.0 work fine.
I assume that there is a bug in XMLDocumentScannerImpl. It has a flag fReadingDTD indicating that currently the DTD is read. If this is true, refresh(int) adds character to a buffer. It seems the end of the DTD is not recognized and the whole XML file is added to the buffer.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the code which creates a large XML file in tmp (i.e. /var/tmp) location, and the OutOfMemoryError will show.

Parse it with the standard SAXParser using at least an EntityResolver that resolves the SystemId.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Should work without any OutOfMemory errors
ACTUAL -
OutOfMemory error

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
        at com.sun.org.apache.xerces.internal.util.XMLStringBuffer.append(XMLStringBuffer.java:205)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.refresh(XMLDocumentScannerImpl.java:1493)
        at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.invokeListeners(XMLEntityScanner.java:2070)
        at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.scanLiteral(XMLEntityScanner.java:1063)
        at com.sun.org.apache.xerces.internal.impl.XMLScanner.scanAttributeValue(XMLScanner.java:974)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanAttribute(XMLDocumentFragmentScannerImpl.java:1537)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanStartElement(XMLDocumentFragmentScannerImpl.java:1314)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2740)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:645)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:508)
        at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:807)
        at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737)
        at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107)
        at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1205)
        at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522)
        at webbugstestcases.jaxp.sax.inc920008.SAXParserTest.main(SAXParserTest.java:71)
Java Result: 1


---------- BEGIN SOURCE ----------
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.StringReader;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;

public class SAXParserTest {
    private static final String DTD =
            "<!ELEMENT config (config*,entry*)*>\n"
                    + "<!ATTLIST config key CDATA #REQUIRED>\n"
                    + "<!ELEMENT entry (#PCDATA)>\n"
                    + "<!ATTLIST entry key CDATA #REQUIRED type CDATA
#REQUIRED value CDATA #REQUIRED isnull CDATA #IMPLIED >";

    private static final EntityResolver RESOLVER = new EntityResolver() {
        public InputSource resolveEntity(String publicId, String systemId)
                throws SAXException, IOException {
            InputSource is = new InputSource(new StringReader(DTD));
            return is;
        }
    };

    public static void main(String[] args) throws
ParserConfigurationException,
            SAXException, FileNotFoundException, IOException {
        // create a huge XML file
        File test = File.createTempFile("test", "xml");
        test.deleteOnExit();
        BufferedWriter out = new BufferedWriter(new FileWriter(test));
        out.write("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n");
        out.write("<!DOCTYPE config SYSTEM
\"org/knime/core/node/config/XMLConfig.dtd\">\n");
        out.write("<config key=\"root\">\n");
        for (int i = 0; i < 1000000; i++) {
            out.write("<config key=\"" + i + "\">");
            out.write("<entry key=\"datacell\" type=\"xstring\"
value=\"org.knime.core.data.def.IntCell\"/>\n");
            out.write("</config>\n");
        }
        out.write("</config>");
        out.close();
       
        // try to parse it
        SAXParserFactory factory = SAXParserFactory.newInstance();
        factory.setValidating(true);
        SAXParser parser = factory.newSAXParser();

        XMLReader reader = parser.getXMLReader();
        reader.setEntityResolver(RESOLVER);

        // java.lang.OutOfMemoryError: Java heap space, even with 256MB heap
        reader.parse(new InputSource(new FileInputStream(test)));
    }
}
---------- END SOURCE ----------


REPRODUCIBILITY :
This bug can be reproduced always.